Conventional methods either use pseudostatic approaches of analysis even for dynamic cases or a simple singledegree of freedom model for the retaining wall soil system. The upper portions of the vertical side walls of the excavation are supported in stages as the excavation is deepened. Kinematic ssi solutions are often formulated for uniform soil conditions, but the shear modulus of most soils is known to increase with mean effective stress, and therefore with depth. The effects of both harmonic and earthquakeinduced excitations are. Earth pressure and retaining wall basics for nongeotechnical. For intermediate cases, the dynamic earth pressures are somewhere between the maximum and minimum value see ref. The method is focused on the building walls rather than retaining walls and specifically considers the dynamic soil properties and frequency content of the design motion in its formulation. Design charts for seismic pressures against rigid walls subjected to horizontal earthquake shaking are presented for both uniform and nonuniform backfills.
The walls of the excavation are pervious enough so that water pressure does not build up behind them. The available methods of dynamic seismic response of retaining walls can be grouped into three categories 1, 2 depending mainly on the degree of modeling elaboration of the soil material. The upper surfaces of the soil layer and the wall are assumed to be free. Experimental results on earth pressures on rigid wall under. This result was expected as pressures are a function of soil displacement and minimal displacements are present in the bedrock layer i.
For the first time wood, et al 1 developed an equivalent static elastic solution for the dynamic soil pressure on nonyielding walls, using linear elastic finite element method 1. This method has generally been used for cohesionless soils only. A new approach for estimating the seismic soil pressure on retaining walls s. Matsuo and ohara 1960 obtained an approximate elastic solution using a twodimensional analytical model.
A complete study to determine the seismic active earth pressure behind a rigid retaining wall by pseudodynamic approach has been carried out by deepankar. A general solution for the determination of total i. Table 2 variations of the dynamic excess pore water pressures. The model incorporates nonlinearity in the behavior of near wall soil, wall exibility and elastic free eld soil response. Keywords retaining walls, rigid walls, dynamic pressure, soil structure interaction. Coefficient k is the ratio of lateral to vertical effective stress at the wallbackfill interface. Evaluation of dynamic soil pressures acting on rigid. The measured distributions of total and dynamic earth pressures, as shown in figures 7 and 8, present that the distributions are nonlinear along the wall height and the amplitude of the earth pressures are proportional to the excited seismic peak accelerations 21, 22. Limit equilibrium analysis imposes a pseudostatic inertial. The problem of analyzing seismic earth pressures on retaining structures is complicated by the fact that it involves a dynamic soil structure interaction that does not lend itself to easy simplification using limit equilibrium.
Dynamic response of underground structures in sand. Dynamic pressures on a pair of rigid walls retaining. For instance a retaining wall can be used to retain fill along a slope or it can be used to. Seismic earth pressures on retaining structures and basement. Vertical pressures for roller compacted concrete wall rcc lateral soil pressures. A new approach for estimating the seismic soil pressure on. In the present work the dynamic wall pressures and the associated forces on a pair of rigid walls experiencing base rotation and retaining a uniform. Dynamic pressures on rigid cantilever walls retaining. Synopsis an effective numerical method for the dynamic analysis of soil pressures on retaining walls has been proposed. Dynamic earth pressure profile on rigid walls, after matthewson et al. Liquefied soil pressures on vertical walls with adjacent.
This work deals with the evaluation of the dynamic pressures and the associated forces on a pair of rigid vertical cantilever walls retaining a uniform, fully saturated poroelastic layer of soil. Pseudostatic lateral earth pressures on brokenback. Lateral earth pressure on nonyielding walls supporting by. The journal aims to encourage and enhance the role of mechanics and other disciplines as they relate to earthquake engineering by providing opportunities for the publication of the work of applied mathematicians, engineers and other applied scientists involved in solving problems closely related to the field of earthquake engineering and geotechnical earthquake engineering. Dynamic soil pressures on rigid cylindrical vaults. A summary is presented of recently contributed simple approximate solutions for the dynamic pressures and the associated forces induced by ground shaking on rigid vertical walls. In the present work the dynamic wall pressures and the associated forces on a pair of rigid walls experiencing base rotation and retaining a uniform, fully. Dynamic soil pressures on rigid vertical walls, earthquake.
Evaluation of dynamic soil pressures acting on rigid culverts. Seismic active earth pressure behind retaining wall. Seismic earth pressure exerted on rigid walls by vertically. Dynamic soil pressures on rigid vertical walls veletsos. This solution is an extension of a previously published analytical model analyzing response of underground structures to vertically propagating waves.
The lateral pressure behind a wall will vary depending on whether the wall is going away from soil or towards soil. Seismic lateral pressures for design of rigid walls wutec. Liquefied soil pressures on vertical walls with adjacent embankments liquefied soil pressures on vertical walls with adjacent embankments okamura, m ishihara, m tamura, k. Static and dynamic active earth pressure springerlink. For the analysis and design of retaining walls in earthquakeprone zones, accurate estimation of dynamic earth pressures is very important.
Design of earth retaining structures for dynamic loads, prof h. Hysteretic damping in the soil skeleton may also be present. Solutions are based on a simplified model of soil response which. A critical evaluation is made of the dynamic pressures and the associated forces induced by ground shaking on a rigid, straight, vertical wall retaining a semiinfinite, uniform viscoelastic layer of constant thickness. Dynamic soil pressures on vertical walls scholars mine.
Numerically, eqd is equal to the horizontal seismic coefficient, k. The base of the soil layer is excited by a harmonic excitation to simulate earthquake conditions. Static behaviour of retaining walls soil pressure distribution. The determination of dynamic seismic lateral earth pressures on foundation walls and retaining walls supporting more than 6 feet 1. Dynamic excess pore water pressures by dynamic soil.
The dynamic excess pore water pressures due to the vertical and horizontal components of earthquakes decrease slightly with the decrease in the degree of saturation from 0. Conventional methods either use pseudostatic approaches of analysis even for dynamic cases or a simple singledegree of freedom model for the retaining wallsoil system. Feb 01, 2006 liquefied soil pressures on vertical walls with adjacent embankments liquefied soil pressures on vertical walls with adjacent embankments okamura, m ishihara, m tamura, k. The effective stress is the intergranular stress calculated by subtracting the pore pressure from the total stress as described in soil mechanics.
They simplified the problem by assuming zero vertical displacement v 0in the soil mass. Dynamic active earth pressure on retaining structures 723 figure 1. The dynamic response of a watersaturated linear poroelastic soil layer over bedrock retained by a pair of rigid cantilever walls to a horizontal seismic excitation is obtained analytically. Horizontal earth pressures on rigid vertical walls in liquefied soils have extensively been studied by many researchers for the level ground surface condition. Seismic earth pressures a technical note oasys software. In this approach, the retaining wall is considered as a vertical flexible beam and the soil is assumed to be a linearelastic material with hysteretic damping. Lateral earth pressures and retaining walls assistant prof.
An analytical model is presented for evaluating the dynamic increment of lateral earth pressure on perfectly rigid unyielding walls. A critical evaluation is made of dynamic pressures and the associated forces induced by ground shaking on a rigid, straight, vertical wall retaining a semi infinite. Dynamic response of soil pressure on retaining wall. Seismic lateral pressures for design of rigid walls guoxi wu and w.
Seismic earth pressures exerted on rigid walls by vertically. Dynamic soil pressures on rigid vertical walls wiley online library. A complete study to determine the seismic active earth pressure behind a rigid retaining wall by pseudo dynamic approach has been carried out by deepankar. For instance a retaining wall can be used to retain fill along a. Pdf using finite element nonlinear analysis, the dynamic soil pressure on perimeter. In this paper, a simple nite element model for seismic analysis of retaining walls is introduced. A soil pressure coefficient, k0e, has been introduced to represent the total static and seismic pressures on a rigid or nonyielding wall. Seismic earth pressures on rigid and flexible retaining walls. In this paper, a series of centrifuge tests was conducted to investigate the effects of embankments resting on ground surfaces on the pressure on the rigid vertical walls. Recognizing the limitation of the mo method, a simplified method was recently developed to predict lateral seismic soil pressure for building walls.
In order to design soilretaining structures such as retaining walls2 and sheet pile walls 3, it is necessary to determine the magnitude of the lateral pressures to which the structure is subjected. The lateral movements of the walls are kept below 1% to 2% of the depth of the excavation. Dynamic soil pressures on rigid vertical walls dynamic soil pressures on rigid vertical walls veletsos, a. On the basis of the limit equilibrium approach and limit state analysis, this paper presents a solution to compute the seismic earth pressure on the back of a retaining wall.
The lateral earth pressure is important because it affects the consolidation behavior and strength of the soil and because it is considered in the design of geotechnical engineering structures such as retaining walls, basements, tunnels, deep foundations and braced excavations. Horizontal earth pressures on rigid vertical walls in liquefied soils with a level ground surface have extensively been studied by many researchers. Yener ozkan august 2003, 101 pages lateral pressures on nonyielding walls due to surface strip loads were investigated considering the nonlinear stressstrain behaviour of the soil by finite. Distribution of seismic earth pressures on rigid retaining walls. The dynamic active earth pressure on retaining structures due to seismic loading is commonly obtained by using the modified coulombs approach which is known as the mononobeokabe method. Dynamic earth pressure myths, realities and practical ways for design carlos coronado and javeed munshi. Dynamic active earth pressure on retaining structures. Weber course content content section 1 retaining walls are structures that support backfill and allow for a change of grade. We examine the influence of vertical heterogeneity of shear modulus on kinematic ssi for rigid walls. During earthquake ground shaking earth pressures on retaining structures can cyclically increase and decrease as a result of inertial forces applied to the walls and kinematic interactions between the stiff wall elements and surrounding soil. Earth pressure and retaining wall basics for nongeotechnical engineers richard p.
Dynamic earth pressure myths, realities and practical. Earthquake engineering and structural dynamics 23 3. Cantilever reinforcement reinforcement counterfort 4. Limit equilibrium analysis imposes a pseudostatic inertial force to a soil wedge behind the wall the mechanism behind the widelyused. Harmonic response of a rigid wall retaining poroelastic soil. This paper examines the dynamic soil pressures and associ. Dynamic poroelastic soil pressures on a pair of rigid. Counterfort strectcher headers filled with soil face of wall 5.
Several researchers have used elastic wave theory to derive seismic soil pressure against a rigid wall. Limit equilibrium analysis imposes a pseudostatic inertial force to a soil. Nevertheless, such simplification is the essence of the most commonly used limit equilibrium method. The dynamic earth pressures are comparatively small for pga less than 0. Pdf proposed dynamic soil pressure diagram on rigid walls.
Arching effect for confined backfill in tall rigid walls. A critical evaluation is made of dynamic pressures and the associated forces induced by ground shaking on a rigid, straight, vertical wall retaining a semi. Beskos department of civil engineering, university of patras, greece abstract the problem of the determination of the dynamic pressures and the associated forces on a rigid, vertical cantilever wall retaining a semiinfinite, uniform, fully. Thus, more research is required in order to clarify the seismic effects on a buried structure. Seismic earth pressures on retaining structures and. Seismic lateral pressures for design of rigid walls. The gravity wall retaining walls are thick and stiff enough that they do not bend.
Dynamic soil pressures on rigid vertical walls technical. The problem of analyzing seismic earth pressures on retaining structures is complicated by the fact that it involves a dynamic soilstructure interaction that does not lend itself to easy simplification using limit equilibrium. Due to the complexity of the soilwall interaction, numerical techniques have recently been adopted to compute the seismic earth pressure against a retaining wall alhomoud and whitman, 1994. Dynamic pressures on rigid cantilever walls retaining poroelastic soil media. Gravity retaining walls fig 1 a are the oldest and simplest type of retaining walls. Soil dynamics and earthquake engineering journal elsevier. Seismic earth pressures of retaining wall from large shaking. Berrak teymur retaining walls are usually built to hold back soil mass 1.
Gazetasa aschool of civil engineering, national technical university, athens, greece bmueser rutledge consulting engineers, new york, usa accepted 11 november 2004 abstract while limitingequilibrium mononobeokabe type solutions are still widely used in designing rigid. The distribution of seismic earth pressures on rigid retaining walls is an important task in design. It has been recognized that time histories of earth pressures during an earthquake consist of the monotonic increase and the dynamic fluctuations. The coefficient of lateral earth pressure, k, is defined as the ratio of the horizontal effective stress.